Experimental Investigation and Evaluation of Newly Designed Electrodes for Hydrogen Production in Alkaline Water Electrolysis

Alkaline water electrolysis is a promising clean hydrogen production technology that accounts for a small percentage of global hydrogen production. Therefore, the technique requires further research and development to achieve higher efficiencies and lower hydrogen production costs to replace the utilization of non-renewable energy sources for hydrogen production. In this study, electrodes are fabricated through fused deposition modelling 3D printing technology for practical and accessible electrolyzer manufacturing, where an initial nickel (Ni) catalyst layer is formed on the 3D printed electrode surface followed by copper modified nickel zinc iron oxide (NiZnFe4O4) layer to investigate a unique electrocatalyst. An alkaline electrolyzer is developed with Ni-NiZnFe4O4 coated 3D printed cathodes and stainless steel anodes to determine the hydrogen production capacities and efficiencies of the electrolysis process. Electrochemical measurements are used to assess the catalyst coated 3D printed electrodes, ranging from physical electrochemistry to electrochemical impedance measurements. The results show that the triangular Ni-NiZnFe4O4 coated electrode with the highest aspect ratio exhibits the greatest current density of −183.17 mA/cm2 at −2.05 V during linear sweep voltammetry (LSV) tests, where it also reaches a current density of −94.35 mA/cm2 at −1.2 V during cyclic voltammetry (CV) measurements. It is concluded that modification of surface geometry is also a crucial aspect of electrode performance, as 30% lower overpotentials are achieved by the rectangular electrodes in this study. The hydrogen production capacities of the alkaline electrolyzer developed range from 4.22 to 5.82 × 10−10 kg/s operating at a cell voltage of 2.15 V. Furthermore, the energy and exergy efficiencies of the alkaline electrolyzer are evaluated through the first and second laws of thermodynamics, revealing the highest energy and exergy efficiencies of 14.34% and 13.86% for the highest aspect ratio rectangular electrode.